Buggy code:
public class ViewsPreferencePage extends PreferencePage implements IWorkbenchPreferencePage { private Button showTextOnPerspectiveBar ; private Button showTraditionalStyleTabs ; private Button enableAnimations ; private Button editorTopButton ; private Button editorBottomButton ; private Button viewTopButton ; private Button viewBottomButton ; private Button perspLeftButton ; private Button perspTopLeftButton ; private Button perspTopRightButton ; int editorAlignment ; int viewAlignment ; String perspBarLocation ; static final String EDITORS_TITLE = WorkbenchMessages . getString ( "ViewsPreference.editors" ) ; private static final String EDITORS_TOP_TITLE = WorkbenchMessages . getString ( "ViewsPreference.editors.top" ) ; private static final String EDITORS_BOTTOM_TITLE = WorkbenchMessages . getString ( "ViewsPreference.editors.bottom" ) ; private static final String VIEWS_TITLE = WorkbenchMessages . getString ( "ViewsPreference.views" ) ; private static final String VIEWS_TOP_TITLE = WorkbenchMessages . getString ( "ViewsPreference.views.top" ) ; private static final String VIEWS_BOTTOM_TITLE = WorkbenchMessages . getString ( "ViewsPreference.views.bottom" ) ; private static final String PERSP_TITLE = WorkbenchMessages . getString ( "ViewsPreference.perspectiveBar" ) ; private static final String PERSP_LEFT_TITLE = WorkbenchMessages . getString ( "ViewsPreference.perspectiveBar.left" ) ; private static final String PERSP_TOP_LEFT_TITLE = WorkbenchMessages . getString ( "ViewsPreference.perspectiveBar.topLeft" ) ; private static final String PERSP_TOP_RIGHT_TITLE = WorkbenchMessages . getString ( "ViewsPreference.perspectiveBar.topRight" ) ; private static final String R21PRESENTATION_ID = "org.eclipse.ui.internal.r21presentationFactory" ; private static final String R30PRESENTATION_ID = "org.eclipse.ui.presentations.default" ; private Combo themeCombo ; private Combo presentationCombo ; private IConfigurationElement [ ] presentationFactories ; private String currentPresentationFactoryId ; private Group createButtonGroup ( Composite composite , String title ) { } protected Control createContents ( Composite parent ) { } private void createPresentationCombo ( Composite parent ) { } private void attachControls ( Control leftControl , Control rightControl ) { } private void createEditorTabButtonGroup ( Composite composite ) { } private void createViewTabButtonGroup ( Composite composite ) { } private void createPerspBarTabButtonGroup ( Composite composite ) { } private void refreshPresentationCombo ( ) { } private void refreshPresentationFactories ( ) { } private void updatePresentationPreferences ( ) { } private void setR30Preferences ( ) { } private void setR21Preferences ( ) { } private void refreshThemeCombo ( ) { themeCombo . removeAll ( ) ; ITheme currentTheme = PlatformUI . getWorkbench ( ) . getThemeManager ( ) . getCurrentTheme ( ) ; IThemeDescriptor [ ] descs = WorkbenchPlugin . getDefault ( ) . getThemeRegistry ( ) . getThemes ( ) ; int selection = 0 ; String themeString = PlatformUI . getWorkbench ( ) . getThemeManager ( ) . getTheme ( DEFAULT_THEME ) . getLabel ( ) ; if ( currentTheme . getId ( ) . equals ( DEFAULT_THEME ) ) { themeString = MessageFormat . format ( WorkbenchMessages . getString ( "ViewsPreference.currentThemeFormat" ) , new Object [ ] { themeString } ) ; } themeCombo . add ( themeString ) ; for ( int i = 0 ; i < ( descs . length ) ; i ++ ) { <START_BUG> themeString = descs [ i ] . getLabel ( ) ; <END_BUG> if ( descs [ i ] . getId ( ) . equals ( currentTheme . getId ( ) ) ) { themeString = MessageFormat . format ( WorkbenchMessages . getString ( "ViewsPreference.currentThemeFormat" ) , new Object [ ] { themeString } ) ; selection = i + 1 ; } themeCombo . add ( themeString ) ; } themeCombo . select ( selection ) ; } protected void createShowTextOnPerspectiveBarPref ( Composite composite ) { } protected void createShowTraditionalStyleTabsPref ( Composite composite ) { } protected void createEnableAnimationsPref ( Composite composite ) { } protected IPreferenceStore doGetPreferenceStore ( ) { } public void init ( org . eclipse . ui . IWorkbench workbench ) { } protected void performDefaults ( ) { } public boolean performOk ( ) { } }

Fix:
themeString = descs [ i ] . getName ( ) ;